Claire Belcher talk

Claire Belcher had to choose between her love of dance and her love of volcanoes. She chose to become a scientist. I approve.

Her job is to educate others, and to measure and quantfy things that help us understand our world better.

Typically our response to fire is about danger and devastation. But fire also does positive things for our planet, including regulating the amount of oxygen in the atmosphere.

Wild fires have been part of Earth’s history for over 400 million years. Claire studies rock layers to understand the incidence of fires. In the south west, there are coals around Bristol from swamplands, red rocks around Exeter from deserts, and the Jurassic coast around Lyme Regis. She has plotted amount of coals and red rocks over 400 million years, and this also indicates the state of the climate.

Red rocks are red because they contain iron oxide, rust. We can say that oxygen levels were lower during the formation of red rocks. What about coals? Photosynthesis releases oxygen into the atmosphere. (We eat plants, and breathe in oxygen, creating an overall balance.) Hence during times when there was lots of vegetation and lots of coal was formed, there was more oxygen in the atmosphere.

At the moment, oxygen forms 21% of the atmosphere. When coals were being formed, oxygen was 10 percentage points higher. 300 million years ago, earth’s system should have gone out of control. What regulated that, to keep oxygen within bounds? The hypothesis is that fire was the regulating force.

The more oxygen, the more fire, and vice versa. And more fires means less vegetation. Fewer fires means more vegetation.

The flammability of forests based on changes in atmospheric oxygen has changed throughout history. But is there any proof that fires have happened at the right times to suppress oxygen? The other by-product of fire is charcoal, which can be preserved for millions of years. So measuring charcoal in rocks can be used as evidence for fires. And the theory matches pretty well.

So fires can regulate oxygen, preventing it on geological timescales from getting too high or too low. What about the modern challenges? We have had a lot of wild fires across the globe, increasing in frequency and destructive power. So maybe ecosystems need to be managed in a way that recognises the relationship with fire.